Could dams be demolished?

Hundreds of dams for hydropower production were built in Finnish rivers in times gone by. What would happen if we started demolishing them?

There are slightly over 150 small hydropower plants in Finland with little or no importance in terms of electricity production. Some of these could be easily demolished for the benefit of aquatic wildlife.

When the dam at Tikkurilankoski rapids in the Vantaanjoki River in Helsinki was demolished and the rapids were restored, trout started spawning in the rapids in the same year and returned to the area after several decades of absence. Bottom weirs that mimic natural obstacles to water flow were built in the river to keep the water upstream of the rapids at its previous level.

Hiitolanjoki, a river discharging into Lake Ladoga, can be cited as another example. This river used to have three small power plants on the Finnish side of the border. Two lower dams have already been demolished, and the last one will meet the same fate in 2023. The released rapids have been restored to their natural condition. The threatened landlocked Ladoga salmon was quick to return to its old spawning grounds after the restoration.

Removing larger power plant dams would not make sense, as these plants make a contribution to climate change mitigation by producing emission-free electricity. Settlements and other activities along the river have also been shaped by the current structure of the river, and demolishing the dams would expose the area to a greater risk of flood damage.

Image: Before the dam was removed and the rapids were set free, Tikkurilankoski was a reservoir for decades. © Harri Aulaskari, ELY Centre.